The subject application relates generally to headers for agricultural harvesters. In particular, the subject application relates to a header including an improved harvester cutter assembly for driving oppositely directed knife blades in linear reciprocating or oscillating fashion.
Agricultural harvesters such as combine harvesters are well known apparatuses for harvesting grain crops. An agricultural harvester is typically a self-propelled vehicle which includes a feederhouse and mechanisms downstream of the feederhouse for separating grain from other crop material. A header is attached to the front of the harvester and includes mechanisms for cutting crop, gathering crop and delivering crop to the harvester's feederhouse. A typical crop cutter includes a stationary knife and a moving knife which together act as shears that cut crop near the ground. After cutting, the crop is gathered, e.g., by a harvesting reel which feeds the cut crop to a conveyor system that transports the cut crop to the harvester's feederhouse.
Typical agricultural harvester cutter assemblies include a pair of oppositely directed knife blades each of which are formed from a plurality of sickle sections that are secured to a knife back. Each knife back, in turn, is connected to a knife drive. In conventional cutter assemblies the knife blades are pivotably connected to the knife drives whereby the knife drives propel the knife blades through a non-linear, arc-like path of motion. In traversing the arc, the knife blades move not only from side to side (i.e., transverse to the direction of movement of the harvester) but also fore and aft (i.e., in the direction of movement of the harvester). The fore and aft motion of the knife blades results in forward and rearward vibration being introduced into the cutter assemblies which adds additional stresses on the knife blades and detrimentally affects the service life of the knife drives.
In addition, the sickle knife drives of current agricultural harvesters are complex in construction with many moving parts including multiple crank shafts and gears. In a typical arrangement, at least one crank shaft and gear is required to drive each knife blade and the interaction of these components must be carefully coordinated in order to move the knife blades in synchronicity. The complexity of such knife drives renders them difficult and costly to manufacture and repair while increasing their susceptibility to failure, which can deleteriously impact harvesting productivity.